1. Technical Field
The present invention relates to a head mounted display.
2. Related Art
A head mounted display (HMD) which is a display mounted on the head is known. The head mounted display generates image light representing an image by using, for example, a liquid crystal display and a light source, and guides the generated image light to user's eyes by using a projection optical system or a light guiding plate, thereby causing the user to visually recognize a virtual image. Of the head mounted display, there are two types including a transmission type in which a user can visually recognize external scenery in addition to a virtual image and a non-transmission type in which the user cannot visually recognize the external scenery. The transmission type head mounted display includes an optical transmission type display and a video transmission type display.
On the other hand, a video camera which is an automatic tracking type image capturing apparatus is known. The video camera receives a signal transmitted from a transmitter attached to an object, specifies a position of the object on the basis of the received signal, and tracks variations in positions of the object, thereby capturing an image of the object.
JP-A-9-74512 discloses a technique in which a position of an object is specified by receiving infrared rays from an infrared transmitter attached to the object and an image of the object can be captured through automatic tracking by moving a camera fixing tripod. In addition, JP-A-9-74504 discloses a technique in which infrared rays from an infrared transmitter attached to an object are received, a specified position of the object is converted into an image signal, and an image which is generated based on the image signal is displayed on a viewfinder of a video camera in correlation with the position of the object. Further, JP-A-9-74505 discloses an automatic tracking type video camera which can easily specify a position of an object by increasing the number of infrared transmitters attached to the object. Furthermore, JP-A-2003-274257 discloses an automatic tracking type image capturing system which receives a signal transmitted from a transmitter attached to an object, specifies a position of the object and acceleration of the object, and performs zooming control according to the acceleration of the object.
However, in the techniques disclosed in the above patent documents, there is a concern that an object cannot be automatically tracked and thus an image thereof cannot be captured when a movement such as speed or acceleration of the object is great. In addition, a user of a video camera which captures an image of an object is required to check whether or not image capturing is normally performed while looking at a viewfinder or a monitor. Thus, there is room for improvement in the image capturing method in order to normally capture an image of an object while visually recognizing the object. Further, in the video camera, there is a case where external scenery which is visually recognized by the user of the video camera is different from external scenery whose image has been captured. Furthermore, it is desirable to specify a position of an object without capturing an image of the object. Moreover, an apparatus which has an image capturing function and is more convenient to use is desirable.